I have a .91 pumper on a vintage 60 size Ultrasport and find it a perfect match. I agree with GNIRWIN that if it is first primed w/o igniter per the mfr instructions, it will fire up easily with a starter, which is no problem for me.
The best aspect of this engine is it's reliability in all attitudes. I have tried to flame it out with just about every neg. G maneuver I can impose, and it has yet to quit. If I had a large amount of time and money invested in a warbird I would probably go for a pumper, which is cheap insurance when the total cost was considered.